Terminal block for electrical measuring instruments.



W. M. BRADSHAW. TERMINAL BLOCK FOR ELECTRICAL MEASURING lNSTRUMENTS.

APPLICATION FILED FEB. 19. 1914.

Patented Dec. 26, 1916.

INVENTOR WITNESSES:

ATTORN TY WILLIAM M. BRADSHAW, OF,WILKINSBURG, PENNSYLVANIA, ASSIGNOR TWESTING- HOUSE ELEC'IRIG AND MANUFACTURING COMPANY, A CORPORATION OFPENNSYL- VANIA.

TERMINAL BLOCK FOR ELECTRICAL MEASURING INSTRUMENTS.

Specification of Letters Patent.

Patented Dec. 26,1916.

Application filed February 19, 1914. Serial N 0. 819,705.

To aZZ whom it may concern:

Be it known that I, WILLIAM M. BRAD- SHAW, a citizen of the UnitedStates, and a resident of Wilkinsburg, in the county of Allegheny andState of Pennsylvania, have invented a new and useful Improvement inTerminal Blocksfor Electrical Measuring Instruments, of which thefollowing is: a

specification.

My invention relates toelectrical measuring instruments and particularlyto terminal blocks for such instruments. I

The object of my invention is to provide a terminal block of such form,dimensions, and structural characteristics as shall adapt it to theservice tobe performed.

Watthour meters are provided with-current windings to be connected inseries relation to the circuits, the energy of which is to be meteredand with voltage windings to be connected in shunt relation to suchcircuits.

It frequently becomes necessary to reverse the positions of theleading-in conductors from left to right, or from right to .left toadapt the meter for either right or left hand feed. In order that thedesired reversal may be effected without placing the Voltage winding insuch connection to the circuit that the current therein will traversethe current windings and be measured, I provide a terminal block thatpermits of the reversal of the voltage winding without disconnecting anyof the conductors.

My invention has. a further advantage in that it is asreadily-applicable to three wire meters as it is to two wire meters. i

In the accompanying drawings, Figure 1 is a plan view of a terminalblock embodying my invention. Fig. 2 is a sectional view taken along theline AA of Fig. 1. 1 Fig 3 is a sectional view taken along the line B-Bof Fig. 1. Fig. 4 is a sectional view taken along the line C-C of Fig.1." Figs. 5, 6 and 7 are detail plan views of. certain metal partsutilized in my invention, Fig.

8 is a diagrammatic view of circuits showing the application of myinvention to a threewire watt meter, and Fig. 9 is a diagrammatic viewof circuits showing the application of my invention to a two-wire wattmeter.

My invention comprises four metal connectors 1, 2, 3 and 4, two metalstraps 5 and 6 and a non-absorbent insulating member 7 'molded aroundthe connectors and straps, substantially as shown in Fig. 1 of thedrawings. The connectors 1 and 2 are respectively provided withlaterally projecting arms 8 and 9 and with screw holes 10 adjacent totheir inner ends. The outer ends of the connectors are provided withrecesses 11 to receive the conductors 12 and 12 of the circuit to bemetered. Transversely disposed screw holes 13 communicate with theopenings 11 to receive binding screws (not shown) for retaining theconductors securely in the openings. The connectors 3 and 4 areseverally provided with screw holes 14 intermediate their ends for thereception of binding screws. The laterally projecting arms ,8 and 9 areprovided, at their extremities with screw holes 15. and 15,respectively, to

receive binding screws, for purposes hereinafter set fort The severalconnectors are located sub stantially as shown in Fig. 1 of the draw-'.

ings, so that the screw hole 15 of the laterally extended'arm 8 of theconnector 1 is substantially above the connector 2 and the screw hole 15of the arm 9 is substantially above the connector 1, though the parts donot come intodirect contact with each other. The metal straps 5 and 6are located between the connectors 1 and 4 and 2 and 3, respectively,for purposes hereinafter set forth.'

The insulating member 7 is molded into such shape as to conform to themeter (not shown) to which it is to be attached, and it has twolaterally projecting portions 16 and 17 which extend into the interiorof the meter, and a mainportion 18 that-has a cavity 18 therein. Theportion 18 is usually located in a receptacle (not shown) that dependsfrom the meter casing- The connectors are so located with respect to themolded member 7 that the outer ends of the screw holes 10 are located atthe outer surfaces of the projections 16' and 17, and the outer ends. ofthe screw holes 14;, 15 and 15 strap.

.. is connected in nections.

are located at the outer bottom surface of the main cavity 18 in theportion 18. Screw holes are provided in the ends of the straps 5 and 6for reasons hereinafter set forth. Holes 19 are drilled into the moldedmember 7 directly in line with the holes 13, and similar holes aredrilled in the front surface of the member 7 directly in line with therecesses 11 for the reception of the conductors 12. The outer surfacesof the front ends of the connectors are substantially lower than theouter surfaces of their rear ends in order to increase the extent ofsurface insulation between the holes 14, 15 and 15 and the holes 13.

Referring now particularly to Fig. 8 of the drawings, two currentwindings 22 and 23 of a watthour meter (not shown) are connected to theinner terminals of the connectors 3 and 41 and 1 and 2, respectively, bythe aid of screws (not shown) which are inserted in the screw holes 10.A voltage winding 24: has its terminals connected to the screws (notshown) which are inserted in the inner holes of the conducting straps 5and 6, The voltage winding 2A shunt relation to the con- 12 byconnecting the interductors 12' and mediate point of the connector 4. tothe.

outer end of the strap 5 and by connecting the hole 15 of the connector1 to the outer end of the strap 6. Two conductors 25 and 26 arerespectively used to make the con- When a change from right to left handfeed is desired, the outer end of the strap 5 is connected to the hole15 of the connector 2 and the outer end of the 6 is connected to theintermediate point of the connector 3, as shown in the dotted lines ofthe drawing. This reversal of the conductors 25 and 26- changes theconnection of the voltage winding 24 with respect to the currentwindings 22 and 23 so that the current that traverses the same will nottraverse the current windings and thus will not be measured.

Referring to Fig. 9'of the drawing, a current winding 27 and a voltagewinding 28 are connected to the respective terminal members of theterminal block, and the in- 'ner ends of the connectors 1 and 2 areconnected together by a conductor 29. The conductors 12 and 12 are theconductors from the line and to the load respectively, as hereinbeforeexplained. The intermedi ate point of the connector 42 is connected tothe outer end of the strap 5 and the hole 15 of the, connector 1 isconnected to the outer end of the strap 6 by conductors 25 and 26,respectively, as hereinbefore; de scribed. When it becomes necessary tore- ,verse the connections of the winding 28 to the conductors of thecircuit by reason of a change from right to left hand feed, theterminals are connected as shown in the part from the spirit of myinvention as defined in the appended claims. A I claim as my invention:

1. A terminal block comprising a plurality positely disposed andlaterally extending arms, a molded insulating member disposed around thesaid connectors, the outer ends of each of the said arms being disposedabove and insulated from the main portion of the adjacent connector.

2. A terminal block comprising a plurality of connectors and aninsulating block molded around the same, said connectors severallyhaving three openings at the top and one opening at one end, saidopenings extending through the said block.

'3. In a terminal block, the combination with a plurality of parallelconnectors severally having binding screw holestherein and openings forreceiving electrical conductors, two of the said connectors havinglaterally disposed and oppositely project ing arms, the ends of whichare disposed substantially above-the other connector, of

a molded structure of non-absorbent insulatingmaterial for supportingand insulating the said connectors.

4i. A terminal block comprlsing two conmolded structure disposed aroundthe connectors for supporting the same and for insulating the connectorsfrom each other.

5. A terminal block comprising a molded insulation member having arecess in the top portion thereof and a plurality of openings in therecessed portion and in one side thereof, a plurality of connectorsdisposed in the molded member, said connectors severally having threebinding screw holes at the top and one opening at one end that areadapted to register with the openings in the molded member.

6. A, terminal block comprising a plu-' ralitv of connectors and aninsulating block molded around the same, said connectors severallyhaving three openings at the top and one opening at one end and two ofthe connectors having laterally disposed and oppositely projecting arms.

7. A terminal block comprising a molded lnsulation member having arecess in the top portion thereof and a plurality of open ings in therecessed portion and in one side thereof, a plurality of connectorsdisposed 1n the molded member, said connectors sev- 3 ofelectricalconnectors having operally having three openings at the top and- Intestimony whereof, I have hereunto subscribed my name this 13th day ofFeb, 10 v1914-.

WILLIAM M. BRADSHAW.

Witnesses:

INA H. BROWN, B. B. HINES.

